Antistatic coatings for plastic vessels

ABSTRACT

A method of reducing static charge of a plastic container is provided. The method includes providing a PECVD coating of SiCOH, SiO x  or SiOH to an external support surface of the container. The PECVD coating reduces static charge of the container compared to a reference container that is essentially identical to the container except that the reference container is uncoated.

FIELD OF INVENTION

The invention relates generally to coatings for plastic vessels, e.g.,containers, to reduce or prevent static charge on the vessels. Moreparticularly, the invention relates to use of vapor deposition coatingson plastic containers to reduce attraction of charged particles to thecontainers, in order to decrease particulate contamination.

BACKGROUND

An important consideration in manufacturing packaging for regulatedproducts, e.g., pharmaceuticals, is to ensure that the pharmaceuticalproduct to be contained within a package is substantially free ofcontaminants. Therefore, processes for manufacturing and fillingpharmaceutical packages with product, are typically performed undercleanroom conditions.

One cause of potential contamination is particulates. Particulatecontamination may originate from various sources, which may be generallydivided into two categories: (1) intrinsic contaminants; and (2)extrinsic contaminants. Intrinsic contaminants are product and processrelated or generated particulates, for example, laser etching residues,filter media, cleanroom uniform fibers, rubber and plastic particlesfrom filter housing, and needle shields. Extrinsic contamination comesfrom sources unrelated to product or process, for example, hair, skincells, pollen, clothing fibers, salt and soil.

While filtration systems and good manufacturing practices can limit thesurface and airborne particulate count in an area where containers arebeing manufactured or filled, these things do not always reduceparticulate count on the container surfaces to acceptable levels. Oneparticular challenge is presented by static charges of manufacturedplastic containers, which tend to attract charged particles. Even if theairborne/surface particulate count is relatively low, a plasticcontainer with a strong static charge can act as a magnet of sorts toattract particulate contaminants and cause them to adhere to thecontainer.

Attempted solutions to this problem include use of antistatic additivesfor polymers, such as ethoxylated alkylamines, ethoxylated alkyl amides,glycerol stearates, fatty acid esters, esters or ethers of polyols andsodium alkyl sulfonates. The amounts of such additives in polymerstypically vary from 0.1% to 3% by weight. While these additives aresomewhat effective in reducing the static charges of plastic articles orvessels that incorporate them, the additives are mobile in the polymermatrix and tend to bloom to the surface. Additives that bloom to thesurface can contaminate the surface and the contents, especially liquidcontents, of a container made from a polymer with such additives.

There is therefore a need for plastic articles or vessels that aretreated to reduce their static charge without the use of typicalantistatic additives, which may themselves be a source of contamination.Likewise, there is a need for methods of treating plastic articles orvessels to reduce their static charge without the use of typicalantistatic additives.

SUMMARY

Accordingly, in one aspect, the invention is a method of reducing staticcharge of a plastic vessel. The method includes providing a PECVDcoating of SiCOH, SiO_(x) or SiOH to an external support surface of thevessel. The PECVD coating reduces static charge of the coated vesselcompared to a reference container that is essentially identical to thecoated vessel except that the reference container is uncoated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a vial according to anembodiment of the present invention.

FIG. 2 is a schematic sectional view of a vial according to analternative embodiment of the present invention.

FIG. 2A is an enlarged detail view of a portion of the vial wall andcoatings of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A “vessel” in the context of the present invention can be any type ofvessel with at least one opening and a wall defining an interiorsurface. The term “at least” in the context of the present inventionmeans “equal or more” than the integer following the term. Thus, avessel in the context of the present invention has one or more openings.One or two openings, like the openings of a sample tube (one opening) ora syringe barrel (two openings) are generally contemplated, althoughvessels with many openings (e.g., microtiter plates) are within thescope of the invention. If the vessel has two openings, they can be ofsame or different size. If there is more than one opening, one openingcan be used for the gas inlet for a PECVD coating method according to anaspect of the invention, while the other openings are either capped oropen. A vessel according to the present invention can be, for example, asample tube, e.g. for collecting or storing biological fluids like bloodor urine, a parenteral container, such as a cartridge or syringe (or apart thereof, for example a syringe barrel) for storing or delivering abiologically active compound or composition, e.g. a medicament orpharmaceutical composition, a vial for storing biological materials orbiologically active compounds or compositions, a pipe, e.g. a catheterfor transporting biological materials or biologically active compoundsor compositions, or a cuvette for holding fluids, e.g. for holdingbiological materials or biologically active compounds or compositions,or secondary packaging (e.g., vial trays). Vessels of other types arealso contemplated. A vessel can be of any shape, a vessel having asubstantially cylindrical wall adjacent to at least one of its open endsbeing preferred. Generally, in optional embodiments, the interior wallof the vessel is cylindrically shaped, like, e.g. in a sample tube,syringe barrel or vial.

In the present disclosure, “thermoplastic material” is defined asincluding polymeric resin compositions. In certain embodiments, thepolymeric resin compositions can be injection moldable resincompositions, which are preferred because injection molded containerscan be made inexpensively, with narrow tolerances and a high level ofautomation. Several specific examples of the polymers from whichthermoplastic compositions can be made, any of which are contemplatedfor any embodiment, are: an olefin polymer; polypropylene (PP);polyethylene (PE); cyclic olefin copolymer (COC); cyclic olefin polymer(COP); polymethylpentene; polyester; polyethylene terephthalate;polyethylene naphthalate; polybutylene terephthalate (PBT);polyvinylidene chloride (PVdC); polyvinyl chloride (PVC); polycarbonate;polylactic acid; polystyrene; hydrogenated polystyrene;polycyclohexylethylene (PCHE); epoxy resin; nylon; polyurethanepolyacrylonitrile; polyacrylonitrile (PAN); an ionomeric resin; Surlyn®ionomeric resin; or a combination of any two or more of the foregoing.

In vessels according to the present invention such as containers (e.g.,laboratory ware, parenteral containers or vials), a chemical vapordeposition coating is applied directly or indirectly on a supportsurface of the vessel. In the non-limiting exemplary embodiment of aplastic (in this case, COP) vial according to the present inventionshown in FIG. 1, the vial 10 includes an internal support surface 12 andan external support surface 14. A coating 16 (which may include a singlelayer or a coating set of more than one layer) applied to the internalsupport surface 12, defines a contact surface 18, i.e., adapted tocontact contents 20 (e.g., liquid contents) of the vial 10 when the vial10 is filled. A coating 22 is also applied to the external supportsurface 14, which defines an antistatic surface 24 adapted to reducestatic charge of the vial 10 compared to a plastic vial without anantistatic surface (i.e., a reference vial).

The coatings 16, 22 are preferably applied using a vapor depositionprocess. While various vapor deposition processes may be used, apreferred example of a vapor deposition process for use according to thepresent invention is plasma enhanced chemical vapor deposition (PECVD).PECVD apparatus and methods for depositing any of the coatings definedin this specification, for example the coatings comprising silicon,oxygen, and optionally carbon identified in this specification, aredisclosed, for example, in WO2013/071,138, published May 16, 2013, whichis incorporated here by reference.

The antistatic surface 24 formed by the PECVD coating 22 optionally canhave many different properties and advantages, depending on how it isapplied and the materials of the external support surface 14 and thecoating 22. Some advantages that can be realized in certain embodimentsof the technology are provided here. The disclosed or claimed technologyis not limited, however, to embodiments implementing one or more ofthese advantages and features.

An optional advantage realized in certain embodiments is that thecontact surface 18 and antistatic surface 24 formed by the PECVDcoatings 16, 22 have improved cleanliness, defined as reduced levels offoreign substances such as particulates, compared to the supportsurfaces 12, 14 before application of the coatings 16, 22, or comparedto a reference vessel or container that is uncoated but otherwiseessentially the same (in terms of size, shape, materials and conditionsof the ambient environment it is exposed to). Another optional advantagerealized in certain embodiments is that the contact surface 18 andantistatic surface 24 formed by the PECVD coating 16, 22 have reducedparticulates and optionally enhanced scratch resistance compared to thesupport surfaces 12, 14 before application of the chemical vapordeposition coating 22, or compared to a reference vessel or containerthat is uncoated but otherwise at least essentially the same. Asdiscussed further herein, it is contemplated that the coating 22 andantistatic surface 24 have antistatic properties that reduce the vial'spropensity to attract particulate contaminants. Optionally, the coating16 and contact surface 18 also have antistatic properties that reducethe vial's propensity to attract particulate contaminants.

Optionally, instead of a single PECVD coating on a support surface of avessel, a coating or layer set may be applied thereon. For example, asshown in the alternative vial 30 embodiment of FIGS. 2 and 2A, theinternal support surface 32 of the vial 30 comprises a tie coating orlayer 34, a barrier coating or layer 36, and a pH protective coating orlayer 38. This embodiment of the container coating or layer set 40 isreferred to herein as a “trilayer coating” in which the barrier coatingor layer 36 of SiO_(x) optionally is protected against contents having apH otherwise high enough to remove it by being sandwiched between the pHprotective coating or layer 38 and the tie coating or layer 34, each anorganic layer of SiO_(x)C_(y) as defined in this specification. In thisembodiment, the pH protective coating or layer 38 (i.e., the outer mostlayer of the coating set 40) defines a contact surface 44, i.e., adaptedto contact contents 20 (e.g., liquid contents) of the vial 30 when thevial 30 is filled. The trilayer coating and the contact surface 44 ofthe trilayer coating may optionally have antistatic properties.

Optionally, a single PECVD coating 42 having antistatic properties maybe applied to the external support surface 46 of the vial 30. Thecoating 42 has an antistatic surface 48. Alternatively, a vial includesonly a single PECVD coating on its internal support surface and itsexternal support surface, or, alternatively, is uncoated on its internalsupport surface and is only coated with a single antistatic coating onthe external support surface. If a single coating is applied to theexternal support surface (or internal support surface), the coating mayoptionally be SiO_(x) or SiOH, or SiCOH. Optionally, the vapor depositedcoating 42 has a thickness of 1 nm to 1000 nm, optionally 1 nm to 900nm, optionally 1 nm to 800 nm, optionally 1 nm to 700 nm, optionally 1nm to 600 nm, optionally 5 nm to 500 nm, optionally 5 nm to 400 nm,optionally 5 nm to 300 nm, optionally 5 nm to 200 nm, optionally 5 nm to100 nm, optionally 10 nm to 100 nm, optionally 10 nm to 75 nm,optionally 10 nm to 50 nm.

Properties of various coatings or layers are now described withreference to FIG. 2A. The tie coating or layer 34, sometimes referred toas an adhesion coating or layer, is provided. The tie coating or layer34 optionally functions to improve adhesion of a barrier coating orlayer 36 to a substrate, in particular a thermoplastic substrate, e.g.,a wall of the vial 30.

Tie Coating or Layer

Optionally, the tie coating or layer 34 comprises SiO_(x)C_(y) orSiN_(x)C_(y), preferably can be composed of, comprise, or consistessentially of SiO_(x)C_(y), wherein x is from about 0.5 to about 2.4and y is from about 0.6 to about 3. The atomic ratios of Si, O, and C inthe tie coating or layer 34 optionally can be: Si 100:O 50-150:C 90-200(i.e. x=0.5 to 1.5, y=0.9 to 2); Si 100:O 70-130:C 90-200 (i.e. x=0.7 to1.3, y=0.9 to 2); Si 100:O 80-120:C 90-150 (i.e. x=0.8 to 1.2, y=0.9 to1.5); Si 100:O 90-120:C 90-140 (i.e. x=0.9 to 1.2, y=0.9 to 1.4); or Si100:O 92-107:C 116-133 (i.e. x=0.92 to 1.07, y=1.16 to 1.33). The atomicratio can be determined by XPS. Taking into account the H atoms, whichare not measured by XPS, the tie coating or layer 34 may thus in oneaspect have the formula Si_(w)O_(x)C_(y)H_(z) (or its equivalentSiO_(x)C_(y)), for example where w is 1, x is from about 0.5 to about2.4, y is from about 0.6 to about 3, and z is from about 2 to about 9.Typically, tie coating or layer 34 would hence contain 36% to 41% carbonnormalized to 100% carbon plus oxygen plus silicon.

Optionally, the tie coating or layer can be similar or identical incomposition with the pH protective coating or layer 38 describedelsewhere in this specification, although this is not a requirement.

Optionally, the tie coating or layer 34 is on average between 5 and 200nm (nanometers), optionally between 5 and 100 nm, optionally between 5and 20 nm thick. These thicknesses are not critical. Commonly but notnecessarily, the tie coating or layer 34 will be relatively thin, sinceits function is to change the surface properties of the substrate.Optionally, the tie coating or layer is applied by PECVD, for example ofa precursor feed comprising octamethylcyclotetrasiloxane (OMCTS),tetramethyldisiloxane (TMDSO), or hexamethyldisiloxane (HMDSO).

Barrier Coating or Layer

A barrier coating or layer 36 optionally can be deposited by plasmaenhanced chemical vapor deposition (PECVD) or other chemical vapordeposition processes on the vessel of a pharmaceutical package, forexample a thermoplastic package, to prevent oxygen, carbon dioxide, orother gases from entering the vessel, the barrier coating 36 optionallybeing effective to reduce the ingress of atmospheric gas into vial 30compared to an uncoated reference vial or container, and/or to preventleaching of the pharmaceutical material into or through the vial wall.

The barrier coating or layer 36 optionally can be applied directly orindirectly to the thermoplastic wall 50 of the vial 30 (for example thetie coating or layer 34 can be interposed between them) so that in thefilled vial 30, the barrier coating or layer 36 is located between theinternal support surface 32 of the wall 50 and the interior of the vial30 that is adapted to contain a fluid, e.g., liquid contents 20, to bestored. The barrier coating or layer 36 of SiO_(x) is supported by thethermoplastic wall 50. The barrier coating or layer 36, as describedelsewhere in this specification, or in U.S. Pat. No. 7,985,188, can beused in any embodiment.

The barrier layer 36 optionally is characterized as an “SiO_(x)”coating, and contains silicon, oxygen, and optionally other elements, inwhich x, the ratio of oxygen to silicon atoms, is from about 1.5 toabout 2.9, or 1.5 to about 2.6, or about 2. One suitable barriercomposition is one where x is 2.3, for example.

Optionally, the barrier coating or layer 36 is from 2 to 1000 nm thick,optionally from 4 nm to 500 nm thick, optionally between 10 and 200 nmthick, optionally from 20 to 200 nm thick, optionally from 20 to 30 nmthick, and comprises SiO_(x), wherein x is from 1.5 to 2.9. For example,the barrier coating or layer such as 36 of any embodiment can be appliedat a thickness of at least 2 nm, or at least 4 nm, or at least 7 nm, orat least 10 nm, or at least 20 nm, or at least 30 nm, or at least 40 nm,or at least 50 nm, or at least 100 nm, or at least 150 nm, or at least200 nm, or at least 300 nm, or at least 400 nm, or at least 500 nm, orat least 600 nm, or at least 700 nm, or at least 800 nm, or at least 900nm. The barrier coating or layer can be up to 1000 nm, or at most 900nm, or at most 800 nm, or at most 700 nm, or at most 600 nm, or at most500 nm, or at most 400 nm, or at most 300 nm, or at most 200 nm, or atmost 100 nm, or at most 90 nm, or at most 80 nm, or at most 70 nm, or atmost 60 nm, or at most 50 nm, or at most 40 nm, or at most 30 nm, or atmost 20 nm, or at most 10 nm, or at most 5 nm thick.

Ranges of from 4 nm to 500 nm thick, optionally from 7 nm to 400 nmthick, optionally from 10 nm to 300 nm thick, optionally from 20 nm to200 nm thick, optionally from 20 to 30 nm thick, optionally from 30 nmto 100 nm thick are contemplated. Specific thickness ranges composed ofany one of the minimum thicknesses expressed above, plus any equal orgreater one of the maximum thicknesses expressed above, are expresslycontemplated.

The thickness of the SiO_(x) or other barrier coating or layer can bemeasured, for example, by transmission electron microscopy (TEM), andits composition can be measured by X-ray photoelectron spectroscopy(XPS).

Optionally, the barrier coating or layer 36 is effective to reduce theingress of atmospheric gas into the vial 30 compared to a reference vialor container without a barrier coating or layer. Optionally, the barriercoating or layer 36 provides a barrier to oxygen that has permeated thewall 50. Optionally, the barrier coating or layer 36 is a barrier toextraction of the composition of the wall 50 by the contents 20 of thelumen vial 30. Optionally, the barrier coating or layer 36 functions todissipate static charge of the vial 30, e.g., to reduce the vial'spropensity to attract particulate contaminants.

pH Protective Coating or Layer

Certain barrier coatings or layers 36 such as SiO_(x) as defined herehave been found to have the characteristic of being subject to beingmeasurably diminished in barrier improvement factor in less than sixmonths as a result of attack by certain relatively high pH contents ofthe coated vessel as described elsewhere in this specification,particularly where the barrier coating or layer directly contacts thecontents. The inventors have found that barrier layers or coatings ofSiO_(x) are eroded or dissolved by some fluids, for example aqueouscompositions having a pH above about 5. Since coatings applied bychemical vapor deposition can be very thin—tens to hundreds ofnanometers thick—even a relatively slow rate of erosion can remove orreduce the effectiveness of the barrier layer in less time than thedesired shelf life of a product package. This is particularly a problemfor aqueous fluid pharmaceutical, diagnostic or biological compositions,since many of them have a pH of roughly 7, or more broadly in the rangeof 4 to 8, alternatively from 5 to 9, similar to the pH of blood andother human or animal fluids. The higher the pH of the contents of acoated container (e.g. the vial 30), the more quickly it erodes ordissolves the SiO_(x) coating. Optionally, this problem can be addressedby protecting the barrier coating or layer 36, or other pH sensitivematerial, with a pH protective coating or layer 38.

The pH protective coating or layer 38 optionally provides protection ofthe underlying barrier coating or layer 36 against contents 20 of thevial 30 having a pH from 4 to 8, including where a surfactant ispresent. For a prefilled pharmaceutical package, for example, that is incontact with the contents of the package from the time it ismanufactured to the time it is used, the pH protective coating or layer38 optionally prevents or inhibits attack of the barrier coating orlayer 36 sufficiently to maintain an effective oxygen barrier over theintended shelf life of the prefilled syringe. The rate of erosion,dissolution, or leaching (different names for related concepts) of thepH protective coating or layer 38, if directly contacted by a fluid, isless than the rate of erosion of the barrier coating or layer 36, ifdirectly contacted by the fluid having a pH of from 5 to 9. The pHprotective coating or layer 38 is effective to isolate a fluid (e.g.,20) having a pH between 5 and 9 from the barrier coating or layer 36, atleast for sufficient time to allow the barrier coating to act as abarrier during the shelf life of the pharmaceutical package or othervessel, e.g., the vial 30.

The inventors have further found that certain pH protective coatings orlayers of SiO_(x)C_(y) or SiN_(x)C_(y) formed from polysiloxaneprecursors, which pH protective coatings or layers have a substantialorganic component, do not erode quickly when exposed to fluids, and infact erode or dissolve more slowly when the fluids have pHs within therange of 4 to 8 or 5 to 9. For example, at pH 8, the dissolution rate ofa pH protective coating or layer made from the precursoroctamethylcyclotetrasiloxane, or OMCTS, is quite slow. These pHprotective coatings or layers of SiO_(x)C_(y) or SiN_(x)C_(y) cantherefore be used to cover a barrier layer of SiO_(x), retaining thebenefits of the barrier layer by protecting it from the fluid in thepharmaceutical package. The protective layer is applied over at least aportion of the SiO_(x) layer to protect the SiO_(x) layer from contentsstored in a vessel, where the contents otherwise would be in contactwith the SiO_(x) layer. The pH protective coating or layer 38 optionallyis effective to keep the barrier coating or layer 36 at leastsubstantially undissolved as a result of attack by the fluid 20 for aperiod of at least six months.

The pH protective coating or layer 38 can be composed of, comprise, orconsist essentially of Si_(w)O_(x)C_(y)H_(z) (or its equivalentSiO_(x)C_(y)) or Si_(w)N_(x)C_(y)H_(z) or its equivalent SiN_(x)C_(y)),each as defined previously, preferably SiO_(x)C_(y), wherein x is fromabout 0.5 to about 2.4 and y is from about 0.6 to about 3. The atomicratios of Si, O, and C in the pH protective coating or layer 286optionally can be: Si 100:O 50-150:C 90-200 (i.e. x=0.5 to 1.5, y=0.9 to2); Si 100:O 70-130:C 90-200 (i.e. x=0.7 to 1.3, y=0.9 to 2); Si 100:O80-120:C 90-150 (i.e. x=0.8 to 1.2, y=0.9 to 1.5); Si 100:O 90-120:C90-140 (i.e. x=0.9 to 1.2, y=0.9 to 1.4); or Si 100:O 92-107:C 116-133(i.e. x=0.92 to 1.07, y=1.16 to 1.33); or Si 100:O 80-130:C 90-150.

The thickness of the pH protective coating or layer as appliedoptionally is between 10 and 1000 nm; alternatively from 10 nm to 900nm; alternatively from 10 nm to 800 nm; alternatively from 10 nm to 700nm; alternatively from 10 nm to 600 nm; alternatively from 10 nm to 500nm; alternatively from 10 nm to 400 nm; alternatively from 10 nm to 300nm; alternatively from 10 nm to 200 nm; alternatively from 10 nm to 100nm; alternatively from 10 nm to 50 nm; alternatively from 20 nm to 1000nm; alternatively from 50 nm to 1000 nm; alternatively from 50 nm to 800nm; optionally from 50 to 500 nm; optionally from 100 to 200 nm;alternatively from 100 nm to 700 nm; alternatively from 100 nm to 200nm; alternatively from 300 to 600 nm. The thickness does not need to beuniform throughout the vessel, and will typically vary from thepreferred values in portions of a vessel.

Optionally, the pH protective coating or layer 38 is at leastcoextensive with the barrier coating or layer 36. The pH protectivecoating or layer 38 alternatively can be less extensive than the barriercoating, as when the fluid does not contact or seldom is in contact withcertain parts of the barrier coating absent the pH protective coating orlayer. The pH protective coating or layer 38 alternatively can be moreextensive than the barrier coating, as it can cover areas that are notprovided with a barrier coating.

The pH protective coating or layer 38 optionally can be applied byplasma enhanced chemical vapor deposition (PECVD) of a precursor feedcomprising an acyclic siloxane, a monocyclic siloxane, a polycyclicsiloxane, a polysilsesquioxane, a monocyclic silazane, a polycyclicsilazane, a polysilsesquiazane, a silatrane, a silquasilatrane, asilproatrane, an azasilatrane, an azasilquasiatrane, an azasilproatrane,or a combination of any two or more of these precursors. Someparticular, non-limiting precursors contemplated for such use includeoctamethylcyclotetrasiloxane (OMCTS).

In the presence of a fluid composition having a pH between 5 and 9contained in the vial 30, the calculated shelf life of the vessel vialis more than six months at a storage temperature of 4° C. Optionally,the rate of erosion of the pH protective coating or layer 38, ifdirectly contacted by a fluid composition having a pH of 8, is less than20% optionally less than 15%, optionally less than 10%, optionally lessthan 7%, optionally from 5% to 20%, optionally 5% to 15%, optionally 5%to 10%, optionally 5% to 7%, of the rate of erosion of the barriercoating or layer 38, if directly contacted by the same fluid compositionunder the same conditions. Optionally, the fluid composition removes thepH protective coating or layer 38 at a rate of 1 nm or less of pHprotective coating or layer thickness per 44 hours of contact with thefluid composition.

PECVD apparatus, a system and precursor materials suitable for applyingany of the PECVD coatings or layers described in this specification,specifically including the tie coating or layer 34, the barrier coatingor layer 36, or the pH protective coating or layer 38, are described inU.S. Pat. No. 7,985,188 and PCT Pub. WO2014164928, which areincorporated herein by reference in their entireties.

Other precursors and methods can be used to apply the pH protectivecoating or layer or passivating treatment. For example, hexamethylenedisilazane (HMDZ) can be used as the precursor. HMDZ has the advantageof containing no oxygen in its molecular structure. This passivationtreatment is contemplated to be a surface treatment of the SiO_(x)barrier layer with HMDZ. To slow down and/or eliminate the decompositionof the silicon dioxide coatings at silanol bonding sites, the coatingmust be passivated. It is contemplated that passivation of the surfacewith HMDZ (and optionally application of a few mono layers of theHMDZ-derived coating) will result in a toughening of the surface againstdissolution, resulting in reduced decomposition. It is contemplated thatHMDZ will react with the —OH sites that are present in the silicondioxide coating, resulting in the evolution of NH₃ and bonding ofS—(CH₃)₃ to the silicon (it is contemplated that hydrogen atoms will beevolved and bond with nitrogen from the HMDZ to produce NH₃).

Antistatic Coatings or Layers

In one aspect, the present invention is a method for applying a PEVCDcoating that dissipates charge build up on a plastic vessel or article,including a film or container. According to some embodiments, and whilenot being limited by the following theory, it is preferred that anantistatic coating is hydrophilic so that water vapor from theenvironment would be attracted to the antistatic coated surface of thevessel. The water molecules would bond with the antistatic coatedsurface through hydrogen bonding. The water hydration layer would be aneffective surface to dissipate charge due to its conductive propertiesand thus reduced surface resistance.

In one embodiment, the antistatic coating is a PECVD applied siliconoxide coating on the vessel, for example, an external support surface ofa container. It is preferred that a silicon oxide coating according tothe present invention is not a dense and high barrier oxide. Highbarrier oxides are highly cross-linked networks of siloxane (i.e. Si—O)bonds with few to no terminating bonds in the network. Terminating bondssuch as silanol (SiOH), silane (Si—H), carboxyl, carbonyl (C═O) andaliphatic bonds (—CH₃) would be eliminated to form a dense matrix. Inthe case of antistatic coatings, polar terminating bonds are desirablebecause of their strong affinity for water. The invention, therefore,according to one aspect, is a silicon oxide coating loaded with silanolbonds or other polar groups. These silicone oxides are not expected tohave high barrier due to their low cross-link density. It iscontemplated that an external support surface of a plastic containerwith a silicon oxide antistatic coating according to the presentinvention, would reduce the attraction of charged particulates to thecontainer, thus reducing contamination.

One benefit of embodiments of the invention is that while the antistaticcoating may provide similar antistatic properties of known antistaticadditives (e.g., as described above) in polymeric materials, suchadditives are mobile in the polymer matrix and bloom to the surface,thus causing contamination. Antistatic coatings according to aspects ofthe invention are permanently and covalently bonded to the underlyingpolymer material. Such permanently bonded surface coatings areadvantageous in that they are immobile and do not serve as a source ofcontamination like antistatic additives. Ultimately, the reduction ofstatic charge reduces the vessel's affinity for visible and sub-visibleparticulates, which are contaminants that affect product yield loss.

Optionally, an anti-static coating according to an aspect of theinvention also provides resistance to scratch (particularly if appliedto thicknesses in micrometers). The coating also optionally provides aclean surface (e.g. substantially free of particulates and resistance tomar and dirt) and additional barrier for air permeation.

Various aspects of the invention will be illustrated in more detail withreference to the following Examples, but it should be understood thatthe present invention is not deemed to be limited thereto.

EXAMPLES Example 1

A study was conducted to evaluate static loading potential and staticdissipation on vial surfaces. 5 ml vials were studied, including thefollowing groups: (Group 1) uncoated COP vials; (Group 2) glass vials;(Group 3) COP vials with internal trilayer coating set; (Group 4)internally uncoated COP vials with external SiO₂ coating; (Group 5)internally uncoated COP vials with external SiOH or SiCOH coating;(Group 6) COP vials with internal trilayer coating set and with externalSiO₂ coating; and (Group 7) COP vials with internal trilayer coating setand with external SiOH coating.

Static was dissipated from parts and work surface with a Static Clean300 mm static bar prior to loading. Parts static loading was achievedvia a ˜500 mm stroke across a cut piece of silk/polyester fabric andreadings were taken from parts hand placed onto a cut piece of ceramic(insulator). Readings were taken with a grounded static meter at adistance of ˜3 cm. The results are as follows:

Group 1: COP Positive (+) Control (Test stopped after 60 seconds) InitalVoltage Final Voltage Time to kV % kV % Dissipate Vial 1 100% 102% —Vial 2 100% 106% —

Group 2: Glass Negative (−) Control (Test stopped after 60 seconds)Inital Voltage Final Voltage Time to kV % kV % Dissipate Vial 1 0% 0% —Vial 2 0% 0% —

Group 3: Trilayer (Test stopped after 60 seconds) Inital Voltage FinalVoltage Time to kV % kV % Dissipate Vial 1 100% 73% — Vial 2 100% 85% —

Group 4: SiO₂ on COP Inital Voltage Final Voltage Time to kV % kV %Dissipate Vial 1 100% 18% 15 sec Vial 2 100% 18% 15 sec

Group 5: SiOH on COP Inital Voltage Final Voltage Time to kV % kV %Dissipate Vial 1 100% 16% 15 sec Vial 2 100% 16% 15 sec

Group 6: SiO₂ on Trilayer Inital Voltage Final Voltage Time to kV % kV %Dissipate Vial 1 100% 29% 15 sec Vial 2 100% 29% 15 sec

Group 7: SiOH on Trilayer Inital Voltage Final Voltage Time to kV % kV %Dissipate Vial 1 100% 16% 15 sec Vial 2 100% 15% 15 sec

As the foregoing data show, uncoated COP has significant static loadingpotential and glass, which is an insulator, does not. The Applicantscontemplated that incorporating glass-like insulation via PECVD coatingson external surfaces of a plastic substrate, e.g., as described above,would facilitate static charge dissipation of the coated substrate(e.g., vial). As the data show, surprisingly, externally coated vials(Groups 4 through 7) dissipate static charge much more quickly and to asignificantly greater degree, compared to uncoated COP (Group 1) andeven COP vials with a trilayer but without an external antistaticcoating (Group 3). It is therefore contemplated that materials with anexternal antistatic coating (e.g., vials of Groups 4 through 7) are farless prone to attract charged particles, and hence less prone toparticulate contamination, than uncoated plastic vessels (Group 1) andthe trilayer vials without an external antistatic coating (Group 3).

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

1.-12. (canceled)
 13. A plastic vessel for containing a liquid product,the vessel comprising an inner surface and an external support surface,wherein at least a portion of the external support surface comprises avapor deposited coating selected from the group consisting of SiCOH,SiO_(x) and SiOH.
 14. The plastic vessel of claim 13, wherein the vesselis made from plastic comprising, consisting essentially of or consistingof one or more of the group consisting of: an olefin polymer,polypropylene (PP), polyethylene (PE), cyclic olefin copolymer (COC),cyclic olefin polymer (COP), polymethylpentene, polyester, polyethyleneterephthalate, polyethylene naphthalate, polybutylene terephthalate(PBT), polyvinylidene chloride (PVdC), polyvinyl chloride (PVC),polycarbonate, polylactic acid, polystyrene, hydrogenated polystyrene,polycyclohexylethylene (PCHE), epoxy resin, nylon, polyurethanepolyacrylonitrile, polyacrylonitrile (PAN), and an ionomeric resin. 15.The plastic vessel of claim 14, wherein the vapor deposited coating isapplied by PECVD.
 16. The plastic vessel of claim 15, the vessel furthercomprising an internal support surface wherein at least a portion of theinternal support surface comprises a PECVD trilayer coating set, thetrilayer coating set comprising a tie layer deposited onto the internalsupport surface, a barrier layer deposited onto the tie layer and a pHprotective layer deposited onto the barrier layer, wherein the tie layercomprises SiO_(x)C_(y) or SiN_(x)C_(y), in which x for the tie layer isfrom about 0.5 to about 2.4 and y for the tie layer is from about 0.6 toabout 3, wherein the barrier layer comprises SiO_(x) in which x for thebarrier layer is from about 1.5 to about 2.9 and wherein the pHprotective layer comprises SiO_(x)C_(y) or SiN_(x)C_(y) in which x forthe pH protective layer is from about 0.5 to about 2.4 and y for theprotective layer is from about 0.6 to about
 3. 17. The vessel of claim16, wherein the vessel is selected from the group consisting of: asample tube, a cartridge, a syringe, a vial, a pipe, a catheter, acuvette and secondary packaging.
 18. The vessel of claim 13, wherein thevapor deposited coating has an effect of dissipating static charge ofthe vessel.
 19. The vessel of claim 13, wherein the vapor depositedcoating further provides one or more of the following features:resistance to scratch, resistance to mar and dirt and a barrier for airpermeation.
 20. The vessel of claim 13, wherein the vapor depositedcoating has a thickness of 1 nm to 1000 nm.
 21. The vessel of claim 20,wherein the vapor deposited coating has a thickness of 5 nm to 500 nm.22. The vessel of claim 21, wherein the vapor deposited antistaticcoating has a thickness of 10 nm to 100 nm.
 23. The vessel of claim 13,wherein the vapor deposited coating is SiCOH.
 24. The vessel of claim13, wherein the vapor deposited coating is SiOH.
 25. The vessel of claim13, wherein the vapor deposited antistatic coating is SiO_(x) havingsilanol or other polar terminating bonds.
 26. The vessel of claim 13,wherein the vessel is selected from the group consisting of: a sampletube, a cartridge, a syringe, a vial, a pipe, a catheter, and a cuvette.27. The vessel of claim 13, wherein the plastic vessel is made fromcyclic olefin polymer (COP) or cyclic olefin copolymer (COC).
 28. Thevessel of claim 13, wherein the plastic vessel is made from cyclicolefin polymer (COP).
 29. The vessel of claim 13, wherein the plasticvessel is a vial.
 30. The vessel of claim 29, wherein the vial is madefrom cyclic olefin polymer (COP) and the coating provides the vial witha final voltage that is 29% of the initial voltage or less after a 15second dissipation time.
 31. The vessel of claim 30, wherein the coatingprovides the vial with a final voltage that is 18% of the initialvoltage or less after a 15 second dissipation time.